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Rear Defroster

Discussion in 'E30 (1984-1993)' started by 348947, Dec 17, 2008.

    348947 guest

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    I own a '87 325IS and the rear defroster does not work. I have checked the fuse, the traces in the rear window as well as using a meter in make sure I there is no break and still nothing. The dash switch lights up but no power seems to be going the the traces. Is there a relay in that curcuit? I would think there would be so it would shut off after a set amount of time. :confused:
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    mooseheadm5

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    It does not shut down after a predetermined time. AFAIK there is no relay. I'll check the wiring diagram and get back to you to tell you where and how to test.

    348947 guest

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    Thanks I really appreciate it. :)
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    alotawatts

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    Grounding checks out.....at least visually for dirty/loose connection ?

    348947 guest

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    Yes, It all seems to look and check on fine. Everything else in the works great so with no visible problems and the dash switch lighing up when depressed I don't know what else to check.
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    mooseheadm5

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    OK. Power comes from fuse 8 in run only (position 2 on the key) so verify that you have battery voltage on both sides of that fuse with key on engine off (or running.) Pull the switch from the console but leave it plugged in. Check for battery voltage at pin 4 (green with blue stripe, hope you are not color blind.) Depress switch and check for battery voltage at pin 6 (black wire.) If you have it there, leave the switch on and check for battery voltage at the connectors on the window. Not sure which side, though. If you have no batt voltage at either connection, but have power out of the switch, there may be a break in the wiring to the back. If you have power at the window check for ground at the other connector on the window. If you don't have ground, the ground point on the body is under the left side of the rear seat.

    94is guest

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    I had a rear defroster switch on my e30 fail in the ON position. I turned the switch off, and I guess it continued to heat the rear window, until it exploded. It was pretty exciting. I thought someone had shot at me. Haha.
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    alotawatts

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    granthr

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    This same thing happened to my friend in his 91 318is!! He also thought he was being shot at. B/C of this I am a little paranoid to use my rear defroster on my E30s. I never leave it on very long. Probably no reason to be worried, but I always think about it when I turn mine on. :confused:

    GR

    94is guest

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    Yeah, I bought a new switch 2 years ago and still haven't used it.
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    az3579

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    Err, how common is this problem? I just reinstalled my switch (after taking it out to make room for the iPod cable for my radio - winter just hit and I regretted having it out!). I don't feel like having the thing die on me after I went through the trouble to fish out the connector all the way at the back of the dash!

    348947 guest

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    Thanks, We just got hamered with over a foot of snow so I will have to wait to test the circuit. The car is parked on the side of my garage covered and buried in snow.:(
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    alotawatts

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    More on grounding. Even if the ground point looks okay you should take it apart and brighten it up with sandpaper, steelwool etc.

    348947 guest

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    Thanks again. I have second question on chips. I was considering installing a power chip in the spring from Bavarian. Is it worth it? They seen to show quite a gain in HP on my model and engine.

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